1. Field of the Invention
The present invention relates to a projector. In particular, it relates to a projector in which the distance between a light source and an optical system producing image light from the light produced by the light source and projecting it is relatively short.
2. Description of the Prior Art
There is a conventional projector known wherein exhaust air from a cooling fan for controlling the temperature rise inside the projector is directed away from a projector lens for projecting an image on a screen so that so-called heat waves caused by hot air entering an optical path of the projection lens is prevented (See, for example, JP-A-10-186546; hereafter called Patent Document 1, JP-A-2002-258248; hereafter called Patent Document 2, and JP-A-2002-341448; hereafter called Patent Document 3).
A projector is sometimes configured such that the distance between a light source producing light and an optical system producing image light from the light of the light source and projecting the image light on a screen is relatively short. With the above configuration, it is relatively easy to design an optical path from the light source to the optical system. Further, devices and members for guiding the light from the light source to the optical system can be eliminated, lowering the manufacturing cost of the projector.
In the projector described above, however, the light source becomes very hot while working. Therefore, the hot air of a cooling fan directed to the light source for preventing the rise in temperature inside the projector may enter the optical system or an optical path of the image light emitted from the projection lens, causing the heat-wave effect described above.